The invention relates to devices for sterilizing liquids, and more particularly to devices for sterilizing and storing saline for ophthalmic purposes, particularly for contact lens applications.
Sterile saline is required by contact lens wearers for use as a rinse solution prior to inserting the lens in the eye, and also for soaking the lens during the sterilization process. The sterility of the solution is important to avoid eye infection. There are several methods of sterilizing and storing saline presently in use. In some cases an autoclave, a device which sterilizes using steam under pressure is used or a heat kit applying electric heat directly to the saline container may be used. One method of storing sterile saline is accomplished by sterilizing small sealed single unit dose plastic packages. Larger plastic bags of solution for intravenous applications may be treated in a similar fashion, but once these containers have been opened, the entire contents must be used immediately and the rest discarded as the saline loses its sterile character.
Heat kits are known which sterilize saline contained in plastic squeeze containers. See for example U.S. Pat. No. 3,801,278 issued Apr. 2, 1974 to Sybron Corporation and U.S. Pat. No. 4,481,410 issued Nov. 6, 1984 to Bortnick. In these devices, the plastic bottles of solution are simply heated within an enclosure to 85-90 degrees Celsius and maintained at that temperature for about 10 minutes. Once the plastic containers have been opened it is necessary to resterilize them before using again. It is also known to use ultrasonic waves to sterilize contact lenses and saline. See U.S. Pat. No. 3,973,760 issued Aug. 10, 1976. The ultrasonic waves heat the solution more gently but over a longer period of time than the heat kits noted above. None of the foregoing apparatus, however, is capable of storing the sterilized saline so that it maintains its sterile character after an initial use.
Sterilized saline for contact lens use has more recently been made available in aerosol cans. This provides an effective method of storage as the internal contents are kept free of contamination by the positive pressure within the can. The expense and environmental problems associated with aerosol spray cans make this a less attractive alternative.
There is therefore a need for an inexpensive supply of sterile saline which can be stored and reused without losing its sterile character. The present invention provides a compact and portable device for providing such a renewable supply of sterile saline.